This invention relates to a spark plug connector for connecting an ignition wire to a spark plug electrode in an internal combustion engine.
An ignition connector for interconnecting a pulse signal to an igniting means (e.g. a spark plug) of an internal combustion engine typically includes a conductive contact having a conductor receiving portion and a spark plug electrode receiving portion. An elastomeric boot can be utilized to enclose a wire end when terminated to the conductor receiving portion of the contact whereby to moisture seal the termination. In present boot assemblies, a user grasps either the wire or the boot to apply the requisite insertion or withdrawal force. Oftentimes the boot has inadequate material for resisting pull forces placed on the boot during its removal from the spark plug. Disadvantageously, this installation could possibly disrupt the termination or deform the contact thereby reducing electrical contact and/or mechanical retention with the electrode.
Insert molding of the boot to the terminated contact is desirable because it is inexpensive and can assist in relieving problems that occur unless the termination is completely sealed, in which case contaminants can enter the terminated area leading to spark erosion of the termination thereby reducing electrical efficiency. Arcing between the wire conductor and contact can erode to the point where the proper functioning of the interconnection will cease altogether.
To overcome these deficiencies, a desirable spark plug connector would have elastomeric material insert molded into and about the contact in such a manner that the termination between the wire center conductor and the contact is protectively embedded in a first body of elastomer and the contact is embedded in the housing in a second body of elastomer, thereby providing an arrangement wherein the installation forces a force engage the elastomer in such a manner that they do not adversely affect the termination.
In accordance with this invention, a spark plug connector for an internal combustion engine includes a rigid dielectric housing, a boot comprised of a first elastomeric material which fills the housing, a metal contact embedded in the elastomeric material having a pair of conductor receiving portions one electrically terminated to the center conductor of a wire and the other configured to connect to the electrode of the spark plug, and a rigid lock sleeve connected to the boot. The housing and the boot include coacting interlocking shoulder portions for transferring forces applied to the housing to the boot when the connector is removed or fitted to the plug. By this arrangement, installation and removal forces applied to the housing do not disturb the relationship between the center conductor of the wire, the contact and boot.
In a preferred embodiment a second elastomeric material, either electrically conductive or nonconductive, is pre-molded about the wire and its center conductor and between the receiving portions when the contact is in a first mold. Thereafter the pre-molded wire assembly and housing are placed in a second mold and the first elastomeric material is insert molded directly into the housing and about the contact to form the boot, the second elastomeric material being used to assure that injection of the first elastomeric material into the housing does not damage the center conductor.
The lock sleeve has a ring portion sized to fit the boot assembly, a serrated tooth from the ring for engaging a groove in the housing to lock to the housing, and a handle to assist in assembly and disassembly with the spark plug whereby to obviate the user grasping the wire or boot. The lock sleeve engages the housing in a manner to compress the housing radially inward with the associated forces on the housing acting to augment engagement of the boot and/or contact to the spark plug.
By insert molding, the elastomeric boot more closely follows the surface contours of the wire and the contact to inhibit contamination, moisture, etc. from attacking the mechanical and electrical interface, so that spark erosion does not occur. Using the handle as a rigid guide reinforces the elastomeric boot to minimize eccentric movements of the contact during mating which may reduce its electrical and/or mechanical efficiency, and inhibit relative movement between the contact, wire and boot that might act to disturb the intimate relationship therebetween.